The spine is a complex structure capable of performing a broad range of kinematic functions. The spinal vertebrae and elastic disk permit the spine to move in three axes of motion. These axes include rotation, such as twisting of the upper back and shoulders relative to the pelvis, horizontal movement, such as forward (anterior) or backward (posterior), and lateral bending movement to either the right or left side.
The spacing between adjacent vertebrae is maintained by a disc having both elastic and compressible characteristics. The appropriate spacing in a healthy spine is maintained between adjacent vertebrae during the rotational, horizontal and lateral movement of the spine, thereby allowing for maximum freedom of motion of the spine. The spacing between adjacent vertebrae is also critical to allow the nerves radiating from the spine to extend outwards without being pinched or compressed by the surrounding vertebrae.
Spinal discs can be damaged by physical injury, disease, genetic disposition, and aging, and become less than fully functional. When this happens, the disc is incapable of maintaining the proper intervertebral spacing and, as a result the nerves radiating from the spine can be compressed. Nerve damage could also be caused by root compression in neural foramen, compression of the passing nerve, and an enervated annulus which occurs when the nerves flow into a cracked annulus that results in pain each time the disc is compressed. Obviously other organic abnormalities can occur in the presence of a dysfunctional disc.
Many solutions have been developed to eliminate or at least minimize nerve compression and the attendant pain that commonly results from spinal nerve pressure. These solutions approach the problem by surgically removing the defective disc and thereafter replacing it with an insert that is subsequently fused to the adjacent discs, thereby maintaining an appropriate distance between adjacent vertebrae. While prior insert solutions have been successful in improving the patient's condition, it is somewhat problematic for the surgeon to gain the necessary access to the space between the vertebrae without doing harm to adjacent body structures such as the spinal cord, other nerves, and other adjacent body organs.
A surgical solution that utilizes a less invasive technique will result in less trauma and unintended damage to surrounding bone, organ, muscle and nerve tissue while achieving the desired results. The present invention relates to an insert that can be advanced into a prepared space between vertebral bodies by a novel instrument, and, upon reaching the appropriate insertion point, a pivotal motion is imparted to the insert to provide proper placement of the insert. The pivotable insert provides the surgeon with the capability to implant the insert using a nonlinear path. The insertion and placement is achieved in a minimally invasive manner.